A first conventional stroller is shown in FIG. 1 generally includes two front leg tubes 100 and two handles 120 connected to the front leg tubes 100 at two respective joint members 110. Each handle 120 has another joint member 111 so as to be pivotably connected to a rear leg tube 130 which is connected to one of two ends of a lower folding link 150, one of two support links 160, and one of two seat tubes 170 by two L-shaped plates 140. Two crossly connected links 180 are connected between the handle 120 and the rear leg tube 130. A folding link 190 is connected between the two links 180. By this arrangement, the stroller can be easily folded by pulling upward. This type of stroller tends to fall and is not satisfied by the customers.
FIG. 2 shows a second stroller wherein the links 181 are U-shaped and pivotably connected in a cruciform style, and a folding link 182 is connected between the two links 181. This U-shaped links 181 occupy too much space which is inconvenient for being stored or even packed.
FIGS. 3 and 4 show a third stroller which includes front leg tubes “A”, two rear leg tubes “B”, two handles “C”, a seat frame “D”, chases links “E” and a backrest frame “F”. A folding link “G” is connected between the tubes of the backrest frame “F”. Two support tubes “H” are connected between the two rear leg tubes “B” and a folding link “I” is connected between the two support tubes “H”. A collapsible tube “J” controls the folding action of the stroller. In order to allow the backrest frame “F” to be pivoted backward, the parallel support tubes “H” are existed. The angle between the rear leg tubes “B: and the handles “C” is sacrificed for allowing the stroller to be folded. In other words, the rear leg tubes “B” have to be two straight tubes and this makes the stroller to be unstable.
The present invention intends to provide a stroller which has stable operation condition and the backrest can be pivoted backward without requiring sacrifice of the structure.